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Abstract

The prey-handling behaviour of two species of Asian ratsnakes was studied in the laboratory. In experiment 1, effects of prey size and type (mouse, lizard and frog) on capture position, direction of ingestion, condition of prey at ingestion, and prey-handling method were investigated using newly hatched Elaphe quadrivirgata. Prey size did not affect these variables except prey-handling method in frog trials: large frogs were more frequently constricted after a delay of more than 1 s than small frogs, and small frogs were usually simply seized. On the other hand, prey type affected prey-handling method: mice and lizards were more frequently constricted or pinioned than frogs. When hatchlings of E. quadrivirgata tried to coil around a prey animal immediately after striking, they frequently failed or released their coils within 10 s after striking. In experiment 2, prey-handling behaviour of adult E. climacophora was examined with mice of various sizes. Adult E. climacophora tended to constrict large mice immediately after striking, whereas they simply seized small mice. Only one out of 38 mice which were constricted immediately after striking was released from the coils within the subsequent 10 s. Large mice were killed prior to ingestion, whereas small mice were swallowed alive. Large mice tended to be swallowed head first. Experiment 3 was conducted to investigate effects of mouse size on prey-handling behaviour of newly hatched E. climacophora. Mouse size affected condition of prey at ingestion and prey-handling method but not capture position and direction of ingestion. Possible relationships between feeding ecology and the differences of prey-handling behaviour among Elaphe are discussed.